The compound, (E)-3-[1-n-Butyl-5-[2-(2-carboxyphenyl)methoxy-4-chlorophenyl]-1H-pyrazol- 4-yl]-2-[(5-methoxy-2,3-dihydrobenzofuran-6-yl)methyl]-prop-2-enoic acid is included within the large generic class of compounds disclosed and claimed in the co-pending PCT application PCT/US 9612581. The compounds are described as existing in either the free acid form or as "pharmaceutically acceptable salts". Example 2 of PCT/US 9612581 gives the method of producing the diacid, (E)-3-[1-n-Butyl-5-[2-(2-carboxyphenyl)methoxy-4-chlorophenyl]-1H-pyrazol- 4-yl]-2-[(5-methoxy-2,3-dihydrobenzofuran-6-yl)methyl]-prop-2-enoic acid. The activity of the compound as an endothelin receptor antagonist is described in PCT/US 9612581.